Intra-Stimulus Recruitment Control

Abstract

Recording evoked neural responses comprises delivering a stimulus from one or more stimulus electrodes to a neural pathway in order to give rise to an evoked compound action potential (ECAP) on the neural pathway. And, recording with measurement circuitry, during delivery of at least part of the stimulus, a neural compound action potential signal sensed at one or more sense electrodes. And, processing the recording of the neural compound action potential signal to determine at least one characteristic of the ECAP. At least one characteristic of the stimulus is then defined based on the determined at least one characteristic of the ECAP.

1 . A device for recording evoked neural responses, the device comprising:
 a plurality of electrodes including one or more stimulus electrodes and one or more sense electrodes;   a stimulus source for providing a stimulus to be delivered from the one or more stimulus electrodes to a neural pathway in order to give rise to an evoked compound action potential (ECAP) on the neural pathway;   measurement circuitry for recording a neural compound action potential signal sensed at the one or more sense electrodes, the measurement circuitry being operable to record the neural compound action potential signal during delivery of at least part of the stimulus; and   a control unit configured to process the recording of the neural compound action potential signal to determine at least one characteristic of the ECAP, the control unit further configured to define at least one characteristic of the stimulus based on the determined at least one characteristic of the ECAP.   
     
     
         2 . The device of  claim 1  wherein the at least one characteristic of the ECAP reflects an efficacy of the stimulus. 
     
     
         3 . The device of  claim 1  wherein the at least one characteristic of the ECAP comprises a binary characteristic. 
     
     
         4 . The device of  claim 3 , wherein the at least one characteristic of the ECAP comprises one of:
 an indication as to whether or not the stimulus has recruited an ECAP; and   a comparison of the ECAP to a threshold.   
     
     
         5 . The device of  claim 1  wherein the at least one characteristic of the ECAP comprises a gradated or scalar indication of an observed feature of the signal. 
     
     
         6 . The device of  claim 5 , wherein the at least one characteristic of the ECAP comprises one or more of:
 a measure of ECAP onset delay time;   a measure of ECAP slope;   a measure of ECAP amplitude such as ECAP peak amplitude;   a measure of ECAP duration such as ECAP peak width, ECAP zero crossing spacing, or ECAP half height width; and   a measure of ECAP spectral components.   
     
     
         7 . The device of  claim 1 , wherein the control unit is further configured to cease recording of the neural compound action potential signal at a time defined relative to detection of a threshold, or at a time defined relative to when the stimulus ceases. 
     
     
         8 . The device of  claim 1 , wherein the control unit is further configured to continue recording of the neural compound action potential signal after the step of defining at least one characteristic of the stimulus is completed. 
     
     
         9 . The device of  claim 1 , wherein the control unit is further configured to determine the at least one characteristic of the ECAP prior to cessation of the stimulus, and to further use the determined at least one characteristic of the ECAP to control the manner in which a remainder of the stimulus is applied. 
     
     
         10 . The device of  claim 9 , wherein the control unit is further configured to use the determined at least one characteristic of the ECAP to alter at least one stimulus parameter in order to control the stimulus to deliver a desired dose of neural recruitment. 
     
     
         11 . The device of  claim 10 , wherein the control unit is configured to control the stimulus to deliver a desired dose of neural recruitment by controlling an amount of charge delivered to the neural pathway by the stimulus. 
     
     
         12 . The device of  claim 10 , wherein the control unit is configured to control the stimulus to deliver a desired dose of neural recruitment by controlling one of a duration, an amplitude, an intensity, a voltage, a current and a morphology of the stimulus. 
     
     
         13 . The device of  claim 1 , wherein the control unit is configured to define at least one characteristic of the stimulus by defining a number of pulses of the stimulus. 
     
     
         14 . The device of  claim 1 , wherein the control unit is further configured to recover any imbalance of charge that occurred as a result of defining at least one characteristic of the stimulus. 
     
     
         15 . The device of  claim 1 , wherein the control unit is configured to define at least one characteristic of the stimulus based on a determined at least one characteristic of at least one previous ECAP. 
     
     
         16 . The device of  claim 1 , wherein one or more of the one or more stimulus electrodes also serve as one or more of the one or more sense electrodes. 
     
     
         17 . The device of  claim 1 , wherein the one or more sense electrodes are non-stimulating electrodes. 
     
     
         18 . The device of  claim 1 , wherein the control unit is further configured to blank the measurement circuitry during one or more stimulus transients. 
     
     
         19 . The device of  claim 18 , wherein the control unit is further configured to unblank the measurement circuitry immediately following a stimulus feature which is expected to cause neural activation. 
     
     
         20 . A method for recording evoked neural responses, the method comprising:
 delivering a stimulus from one or more stimulus electrodes to a neural pathway in order to give rise to an evoked compound action potential (ECAP) on the neural pathway;   recording with measurement circuitry, during delivery of at least part of the stimulus, a neural compound action potential signal sensed at one or more sense electrodes;   processing the recording of the neural compound action potential signal to determine at least one characteristic of the ECAP; and   defining at least one characteristic of the stimulus based on the determined at least one characteristic of the ECAP.   
     
     
         21 . The method of  claim 20 , wherein the at least one characteristic of the ECAP reflects an efficacy of the stimulus. 
     
     
         22 . The method of  claim 20  wherein the at least one characteristic of the ECAP comprises a binary characteristic. 
     
     
         23 . (canceled) 
     
     
         24 . The method of  claim 20  wherein the at least one characteristic of the ECAP comprises a gradated or scalar indication of an observed feature of the signal. 
     
     
         25 . (canceled) 
     
     
         26 . The method of  claim 20 , further comprising ceasing recording of the neural compound action potential signal at a time defined relative to detection of a threshold, or at a time defined relative to when the stimulus ceases. 
     
     
         27 . The method of  claim 20 , further comprising continuing recording of the neural compound action potential signal after the step of defining at least one characteristic of the stimulus is completed. 
     
     
         28 . The method of  claim 20 , further comprising determining the at least one characteristic of the ECAP prior to cessation of the stimulus, and using the determined at least one characteristic of the ECAP to control the manner in which a remainder of the stimulus is applied. 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . (canceled) 
     
     
         33 . (canceled) 
     
     
         34 . The method of  claim 20 , wherein defining at least one characteristic of the stimulus is based on a determined at least one characteristic of at least one previous ECAP. 
     
     
         35 . (canceled) 
     
     
         36 . (canceled) 
     
     
         37 . The method of  claim 20 , further comprising blanking the measurement circuitry during one or more stimulus transients. 
     
     
         38 . (canceled) 
     
     
         39 . A non-transitory computer readable medium for recording evoked neural responses, comprising instructions which, when executed by one or more processors, causes:
 delivering a stimulus from one or more stimulus electrodes to a neural pathway in order to give rise to an evoked compound action potential (ECAP) on the neural pathway;   recording with measurement circuitry, during delivery of at least part of the stimulus, a neural compound action potential signal sensed at one or more sense electrodes;   processing the recording of the neural compound action potential signal to determine at least one characteristic of the ECAP; and   defining at least one characteristic of the stimulus based on the determined at least one characteristic of the ECAP.